When Aleah found out she was expecting on "16 and Pregnant," it wasn't something she could have ever imagined for herself, especially because she’d been on the birth control shot, Depo-Provera. Even though she hadn’t received a shot in a while, she hadn’t gotten her period, so she thought she was safe. So how did she end up pregnant?

First off, kudos to Aleah for choosing Depo. As one of the most effective methods, Depo-Provera (pronounced like Johnny Depp-oh), is long-lasting, private and a good hormonal choice for those who can’t take estrogen. You only have to go to the doctor or clinic for an injection once every three months -- but, as Aleah learned the hard way, if you miss an appointment, there's a good chance it WON'T work. With perfect use, the shot is more than 99 percent successful.

As for Aleah not thinking she could even get pregnant because she hadn’t gotten her period, that’s a side-effect of the shot: Irregular bleeding, especially for the first 6-12 months, is pretty common.

Depo is one of those methods that is easy to use, doesn’t interrupt the heat of the moment, doesn’t require daily maintenance and is super private. But it’s only one of many options. For more about the different kinds of birth control available, check out Bedsider.org. Plus, visit MTV’s It’s Your Sex Life website for info on teen pregnancy and sexual health.